Automated storage libraries including, for example, magnetic tape cartridges, may improve the access speed and reliability of data storage systems having large numbers of magnetic tape cartridges. Automated storage library systems typically include a plurality of storage media devices, a transport mechanism, and one or more storage media drives in communication with a computer system for inputting and outputting desired information to and from the plurality of media devices.
Storage media devices such as cartridges housing magnetic tape with data stored thereon have proven to be an efficient and effective medium for data storage in computer systems, including automated storage libraries. Automated storage libraries including tape cartridges generally have a plurality of storage panels with magazines for storing tape cartridges, a retrieval/transport mechanism (often referred to as a “robot”), and one or more tape drives. The transport mechanism may be controlled to select a specific storage tape cartridge from the library and transfer the tape cartridge between a storage slot and a tape drive within seconds. The transport mechanism typically is associated with a gripper or hand mechanism (often referred to as a “picker”) positioned on the transport mechanism to controllably retrieve and transport a tape cartridge within the storage library.
In order to be able to store the maximum amount of data in the least amount of space, the ideal data storage library would have the tape cartridges organized so that the maximum storage density per square foot is obtained. Unfortunately this may prohibit access to some of the media. Most storage libraries have fixed storage panels or racks for the cartridges. Previously, to increase storage density in automated tape libraries, tape cartridges have been organized in rotating towers, stacking tape cartridges at least two deep in a storage rack, stacking tape cartridges in a removable tray, and storing tape cartridges back-to-back, for example.
However, these types of systems require complex systems for accessing the tape cartridges. Furthermore, most of these approaches rely on relatively fixed tape cartridge locations. All of these libraries also place approximately the same priority to accessing any cartridge even though some data may not be used for extended periods of time.
Therefore, a media storage library with minimal space between cartridges to achieve high densities and areas within that library that can be assigned lower exchange rates (i.e., high frequency of use versus low frequency of use), is desired.